Eyeglasses or spectacles are manufactured in a wide variety of shapes and configurations tailored to different needs and preferences of the eyeglasses wearer. Rimless spectacles provide many advantages over traditional framed spectacles such as an improved, less obstructed field of view and lightness in weight. Many different styles of spectacles are known in the art.
U.S. Pat. No. 5,684,588 to Hamamoto discloses semi-rimless spectacles comprising a pair of lenses each having an upper and lower edge portion, the upper edge portion of each lens being fitted in a section of metal frame, and the lower edge portion having a groove cut along its edge surface. A nylon thread is laid along the groove in the lower edge portion of each lens, and the opposite ends of the thread are fastened to the upper metal frame whereby the lenses are suspended. One disadvantage of rimless spectacles of this type is that the metal frame is visible on the wearer of the spectacles, even a significant distance. Other disadvantages are that the metal frame creates an obstruction in the field of view of the wearer, and increases the overall weight of the spectacles. For many eyeglass wearers, it is desirable to have spectacles that have less visible frames and which provide a less obscured view.
A type of rimless spectacles uses lenses which are supported by means of screws fitted into holes formed through the surface of each lens. Small screw holes, typically 1.4 mm in diameter, are bored through portions of each lens close to its respective hinge edges where the sidearms are attached. Screws are threaded into the holes to attach the lenses to other structural components of the spectacles such as the sidearms and bridge. Examples of rimless spectacles of this type can be found in Japanese Utility Model Publication No. 4-63419 and U.S. Pat. No. 4,692,001 to Anger. A disadvantage of spectacles of this type is that during the formation of the exit hole for the screws, the lens may be chipped. Also, the act of threading a screw into the bored screw holes may crack the lens surface. In some applications, screw hole cracking is minimized by boring screw holes at a distance from the edge of the lens. However, this approach obstructs the field of view of the wearer of the spectacles by placing screws and nuts and/or other spectacle components further away from the edge of the lens and more directly in the wearer's field of view. Furthermore, because screws, nuts and/or other spectacle components attached to the lenses protrude from the surfaces of the lenses, they form an obstacle during cleaning of the lenses.
U.S. Pat. No. RE37,461 E to Izumitami discloses a frame for rimless spectacles that does not use projections from the surface of the lens. Blind holes are bored in the nose-side and temple-side edge portions of each spectacle lens. Pin-like projections are attached to the sidearm and bridge, and are inserted into the corresponding blind holes in the lens and are fixed with an adhesive. A disadvantage of rimless spectacles of this type is that the pins carry the majority of the load created by the lenses and are responsible for the strength of the connection of the lenses to the other spectacle components. To support the spectacles, the pins are longer and larger in diameter than is aesthetically desirable by many eyeglass wearers. To prevent rotational movement, at least two pins must be used at each attachment point. The size and number of pins required by spectacles of this type also create an obstruction in the wearer's field of view. Furthermore, the pins must be fixed within the corresponding blind holes using an adhesive. The use of an adhesive complicates the manufacturing process of the spectacles and may increase the obstruction in the wearer's field of view caused by the pins. Thus, it is desirable to have rimless spectacles that are more aesthetically pleasing and which have a less obscured field of view.